This invention relates to a laser medical apparatus used, for example, in plastic surgery or dermatology, and, more particularly, to a laser medical apparatus which is adapted for the eradication or medical treatment of pigmented naevi consisting of abnormal blood vessel or pigmented cell agglomerations by radiating laser beams having a proper amount of energy onto said agglomerations.
Hitherto, various medical treatments of naevi have been attempted in the fields of surgery, dermatology and radiopathology. Namely, surgical medical treatment such as excision, suture, skin grafting and surface skin exfoliation. In dermatology, pharmacotherapy, dry ice and electrolysis treatment are used. Radiotherapy involves the application of radium, cobalt, strontium, etc. The above-listed processes may be considered the main types of medical treatment. However, these treatments have the drawback that despite the major invasion of the body a satisfactory therapeutic effect cannot be obtained. Moreover, surgical treatment is painful and sometimes requires long hospitalization. Consequently, a strong demand has been made for the improvement of the treatment.
In recent years, histological research has been conducted on naevi and the origin of the naevi is being studied, but progress is slow. Abnormal pigmented cells observed in, for example, the so-called vascular naevus are generally less transparent than normal cells, and absorb visible light rays more strongly than the normal transparent cells. Therefore, visible high energy light rays radiated on said abnormal cells are selectively absorbed, and changed into heat energy. As a result, the abnormal cells are broken down due to intense burning. Conversely, the normal cells have higher transparency and absorb little of the above-mentioned high energy light rays, resulting in less heat damage. Consequently, the radiation of the aforementioned high energy light rays on the pigmented naevi causes only the abnormal cells to be selectively burnt off. In this case, the more transparent normal cells, perspiratory glands and tissue absorb little light, and are not irreversibly damaged. Therefore, the burnt normal cells and tissue are rapidly healed with only minute cicatrices remaining. If, therefore, it is possible to select such visible light wavelengths whose light energy is absorbed less by the normal cells of the naevi of the diseased spot and is absorbed to a greater extent by the pigmented cells, and if it is possible to set the energy density of said wavelengths at a prescribed level, then the pigmented cells can be selectively destroyed. Laser beams are light rays which satisfy the above-mentioned requirements.
At present, various laser medical apparatuses have been proposed. FIG. 1 denotes one type of such an apparatus. Reference numeral 1 denotes an apparatus body. The body 1 comprises a power source 1A, laser oscillator 1B and operation panel 1C. Laser beams issued from the laser oscillator 1B are conducted through an optical fiber 3 and ejected from the distal end of a hand piece 4. Argon laser rays, which have a typical wavelength of 5,140 .ANG., and ruby laser rays, which have a typical wavelength of 6,943 .ANG., provide a relatively large output of a visible light range effective for the treatment of pigmented naevi and are now being used in practical applications. The ruby laser beams can provide high light energies and a broad radiation area, but have the drawback that the ruby laser beams are issued by pulse oscillation and require a longer overall radiation time, thereby lengthening the treatment period. Conversely, the argon laser beams have the drawback that they provide a lower light output (about several watts) than the ruby laser beams, but have the merit that they can be better controlled and are radiated on a relatively small area. Moreover, they can be operated and handled at a higher speed and are more adapted for the treatment of a delicate structures.
The above-mentioned laser medical apparatus is generally used by holding the hand piece 4. While the operator observes the diseased spot, the spot on which the laser beams are to be radiated is progressively shifted by an extent corresponding to the flux of the laser beams radiated from the end of the hand piece 4. The operator carries out treatment by radiating laser beams intermittently or continuously using a pedal switch, for example.
However, in the laser flux issued from the laser oscillator, the energy intensity progressively decreases from the center to the peripheral portion as seen from FIG. 2. This is called Gauss' distribution. FIG. 2a indicates Gauss' distribution by planar contour lines. FIG. 2b is a 3-dimensional view of Gauss' distribution.
When laser beams which have different energy intensities are radiated on a patient's diseased spot, radiation irregularities arise in accordance with the different energy intensities as typically set forth in FIG. 3a. It is therefore necessary to apply such an amount of laser beams as can heal the patient's diseased spot without causing ugly cicatrices or scars to be left at the central portion of said diseased spot in which the highest laser beam energies tend to concentrate. The requisite conditions by which the laser beam energy should be determined are being clarified from animal tests and clinical experience. At present, it is possible to determine the types of patient reaction to laser beams, and the extent of the cicatrices remaining, according to the magnitude of the laser output and the volume of its flux (that is, the area of laser radiation). Further, it is possible to determine the efficiency of radiant heat and propagated heat by measuring the laser beam radiation time, and also to define the moisture quantity in the case of thermal treatment and the cooling effect of blood by measuring the intervals at which laser beams are radiated.
FIG. 3b illustrates the case where a plurality of linearly arranged laser beam fluxes having a radiation diameter d are ejected under uniform conditions. It has been determined from clinical experience that the purpose can be attained if the pitch P between the respective laser beam fluxes, that is, the overlapping rate thereof, corresponds to 30 to 40% of the radiation diameter d. FIG. 3c shows the condition of a diseased spot which has been subjected to the radiation of laser beams and which has been healed after a certain lapse of time without any marks or cicatrices.
Description will be given with reference to FIG. 4a of the process of radiating laser beams on a patient's diseased spot. A plurality of laser fluxes linearly arranged in a partially superposed fashion are radiated. Thereafter, a similar group of laser fluxes are radiated near the above-mentioned laser fluxes at an interval d.sub.1, which is smaller than the radiated diameter d of said laser fluxes. This second laser flux-radiated spot is referred to as "D.sub.1 ". Namely, the radiation of laser fluxes is carried out in a zebrine pattern. This zebrine pattern laser flux-radiating process is deemed the best method whose efficacy has been proved by experiments undertaken in regards to the effect of radiated heat and propagated heat and the cooling effect of the blood. FIG. 4b shows the patient's diseased spots which were subjected to the above-mentioned zebrine pattern laser flux-radiating process, and which resulted in the healed conditions D', D'.sub.1 after the lapse of a certain length of time.
FIG. 5a illustrates laser fluxes applied to the non-radiated intervening section of the zebrine pattern laser flux-radiating process of FIG. 4b. FIG. 5b indicates the patient's diseased spots which were healed after a lapse of a certain length of time by the application of the zebrine pattern laser flux-radiating process on the intervening spaces shown in FIG. 4a.
An actual medical operation with the above-mentioned laser apparatus is carried out in the following manner. The operator grips the hand piece 4, and moves the wrist to set the hand piece 4 perpendicular to the surface of the diseased spot. The operator holds the hand piece 4 in such a manner that the output end face is at a prescribed distance from the diseased spot. While observing that portion of the diseased spot which is to be subjected to laser beams, the operator linearly moves the hand piece 4 to an extent corresponding to the total length of the plurality of laser fluxes linearly issued from the hand piece 4 in succession and in a partially superposed fashion. The medical treatment is performed by continuously or intermittently radiating laser beams by actuating a pedal switch, for example. The reason why the hand piece 4 is spaced away from the patient's diseased spot at a certain distance is to prevent the laser beam output from being reduced or the end face of the hand piece fiber from being contaminated due to the blood or flesh particles splattering from the diseased or applicated spot onto said fiber end face during the laser treatment.
However, the surface of the diseased spot and the distal end of the hand piece 4 are not generally brought into contact with each other. Therefore, it requires considerable skill to securely hold the hand piece 4 perpendicularly to the diseased spot and at a prescribed distance. Further, tremendous difficulties are encountered in uniformly arranging with the naked eye the circles of the radiated laser fluxes (generally having a diameter of about 2 mm) or preserving a prescribed interval between the respective radiation circles of partially superposed laser fluxes arranged in the zebrine pattern (i.e., an interval between the centers of the circles). If, therefore, the arrangement of the circular radiated laser fluxes is rendered irregular, and the respective radiated laser fluxes are superposed on each other to an excessive extent, the diseased spot may be excessively destroyed, resulting in cicatrices, which harmfully affects the laser treatment. If the respective groups of the radiated circular laser fluxes are spaced from each other too broadly, the intervening regions will remain untreated. If it is impossible to preserve the prescribed energy density of radiated laser fluxes (a product of the radiation time and the distance between the respective circles of radiated laser fluxes, assuming that the laser output remains constant), then the respective laser fluxes tend to produce burn marks. Laser fluxes having a greater energy density than is required for the temperature rise of the abnormal cells of the diseased spot are particularly likely to indiscriminately heat the surrounding non-diseased cells which require no laser treatment, thereby destroying normal cells.
As mentioned above, the conventional laser medical apparatus used in plastic surgery or dermatology has various drawbacks. When applied to actual medical treatment, the practicality of the conventional laser apparatus is reduced, if the diseased spot is too broad. If the treatment continues for a long time, the operator will tire and the patient must maintain a certain posture for a long time without moving. Also, considerable difficulties are encountered in carrying out an effective laser treatment and the operator must use great skill.